Lytham St Annes: Americans Zach Johnson and Bubba Watson maintained their country's fine recent form in major championships with excellent opening rounds in the British Open on Thursday.

Johnson's 65 left him one shot behind early leader Adam Scott and Watson, the U.S. Masters champion, carded a 67 to finish level with compatriot Tiger Woods and give the United States a powerful presence at the top of the leaderboard.

Johnson, the 2007 Masters winner, struck seven birdies before bogeying the 17th to leave a slightly sour taste in his mouth.

"I was extremely annoyed," the winner of last week's John Deere Classic told reporters. "I knew I had a lot of work to do this week.

"For the most part there's a lot of momentum coming from last week. But I've forgotten about it.

"Obviously I played well here but it's just one day. I'm going to grab those positive feelings I had last week. But for the most part a new week, completely different elements, completely different golf course."

Johnson is adopting a simplistic approach to the rest of the tournament.

"Quality shots," he said. "That's really all you can do here. I feel it's one of those tournaments where if you hit bad shots it's usually a bad result.